Figure 3. cAMP amplifies IFN-γ and IL-2 signalling through induction of IFN-γR1 and IL-2Rβ.

(a) Expression of Il12rb2 mRNA in T cells activated with αCD3/CD28 for 24 h with addition of db-cAMP or cycloheximide (CHX) or both for the last 12 h. (b) Profile of db-cAMP-dependent expression of cytokines and their receptors by WT or IFN-γR1^−/− T cells activated for 12 h with αCD3/CD28 followed by treatment with db-cAMP or vehicle for another 3 h. Data shown in bar graphs represents fold change (db-cAMP versus vehicle) in mean intensity from each probe in biological duplicates. The probe for Ifngr1 in this array is targeted to a segment of sequence in the exon VII, while The IFN-γR1^−/− mouse that we used has Ifngr1 gene disrupted by inserting the neomycin resistance gene into exon V. (c,d) Expression of IFN-γR1 mRNA (c) and protein (d) in T cells stimulated with or without αCD3/CD28 in the absence or presence of db-cAMP for 12 h. (e) Immunoblot for p-STAT1 (Y701) and STAT1 in T cells pretreated with db-cAMP for 12 h, washed and restimulated with 1 ng ml⁻¹ IFN-γ for another 30 min. (f) Expression of Il2rb mRNA in T cells treated with db-cAMP for 12 and 24 h. (g) IL-2Rβ protein expression in T cells activated with αCD3/CD28 for 2 days, allowed to rest for another 2 days, then restimulated with db-cAMP in the presence of IL-2 for 24 h. Data shown as mean±s.e.m. are representative of two independent experiments with triplicates (a,c–g) or are from one experiment (b). a.u., arbitrary units.